Sea urchin species on brink of extinction after marine pandemic

"Since 2021, Diadema africanum urchins in the Canary Island archipelago have almost entirely been killed by an unknown disease. There has been a 99.7% population decrease in Tenerife, and a 90% decrease off the islands of the Madeira archipelago. In the same period, mass deaths have been detected in species from the Red Sea, Mediterranean, Caribbean and western Indian Ocean."

"Sea urchins are remarkable creatures. A relative of the starfish, they breathe through their feet, and while their spikes are a formidable defence against predators, they also provide refuge for smaller marine creatures. They are known as ecosystem engineers, and affect their surroundings by grazing on algae, breaking down food for other animals, and acting as food for predators. By controlling algal growth they promote the survival of hard coral, itself the habitat for thousands of marine species."

"Their loss has been felt in Caribbean reefs, where coral cover has halved and algal cover increased by 85%. Mass deaths have been detected in the Red Sea, Mediterranean and Caribbean. Photograph: Ibrahim Chalhoub/AFP/Getty Images What fascinated me in the first place about this species is that they change their environment. Like humans, when they are present, they modify their habitat, said Cano. We don't know the cascading effect that this could have in other species."

Since 2021 an unknown disease has almost entirely killed Diadema africanum in the Canary Islands, producing a 99.7% decline in Tenerife and a 90% decline off Madeira. Mass mortality events have also been recorded in the Red Sea, Mediterranean, Caribbean and western Indian Ocean. Sea urchins function as ecosystem engineers by grazing on algae, providing refuge, breaking down food and serving as prey; their grazing supports hard coral survival. Caribbean reefs have seen coral cover halve while algal cover increased by 85%. Scientists do not know the exact cause; human-mediated spread and changes to currents, shipping and wave activity are possible.

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